LTS - Long Term Support
EOL - End Of Life
Ubuntu
http://www.ubuntu.com/info/release-end-of-life
When an Ubuntu release reaches its “end of life” it receives no further maintenance updates, including critical security upgrades. It is highly recommended that you upgrade to a recent version of Ubuntu at this point.
LTS 版本比普通版本支持周期长：
Standard Ubuntu releases are supported for 9 to 18 months. Previous Ubuntu LTS (Long Term Support) releases are now supported for five years on both the desktop and the server. During that time, there will be security fixes and other critical updates.
Fedora
Fedora Project maintains each release of Fedora according to the Fedora Release Life Cycle. The following releases have reached End of Life, and are no longer maintained and do not receive any updates.
